Tires that are not optimally pressurized contribute to low fuel efficiency. These effects are particularly felt in the trucking industry, where long distances and large loads amplify the effects of an underinflated tire. However, it is often inconvenient and inefficient for truck drivers to constantly stop, check, and inflate the vehicle tires to the optimal pressure, leading to the persistence of less-than-optimal fuel efficiency in most trucks. This problem has led to several auto-inflating tire systems. Conventional auto-inflating tire systems are either central or distributed, but each suffers from its own set of drawbacks. Central inflation systems are complex and expensive, and require significant work for aftermarket installation (drilling through axles, tapping existing air lines, etc). Distributed systems are mounted at each wheel and can be less expensive, but the potential for reduced cost is typically at the expense of the continuous replacement of the device (which fails due to the harsh wheel environment).
Furthermore, passive pressurization systems can be desirable for tire inflation applications, as electrical energy storage mechanisms and programming can be eliminated from the system. However, conventional passive pressurization systems suffer from several problems. First, conventional passive pressurization systems using reciprocating pumps oftentimes suffer from fatigue due to the high pressures and high number of pumping cycles that are demanded. Second, passive pressurization systems can suffer from over-pressurization of the reservoir, wherein the pressurization system continues to pump fluid into the reservoir even after the desired reservoir pressure is reached. Conventional systems typically resolve this problem with a relief valve, wherein the relief valve vents the reservoir contents into the ambient environment when the reservoir pressure exceeds the desired pressure. This results in a loss of the already-pressurized fluid, resulting in additional pump cycles to bring fluid at ambient pressure up to the desired pressure, thereby resulting in a shorter pump lifetime. Third, conventional eccentric-mass driven pump systems, such as pendulum systems, experience instabilities when the rotating surface to which the eccentric mass is coupled rotates near the excitation frequency for the given eccentric mass. More specifically, the eccentric mass rotates with the system at this excitation frequency, resulting in radial oscillations that can be detrimental to the overall system or to the rotating surface to which the pump system is coupled.
Thus, there is a need in the pumping field to create a new and useful pump.